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kobusy [5.1K]
3 years ago
8

A student is told that both energy and mass must be conserved in every chemical reaction. She measures the mass of Hydrochloric

acid and a zinc strip separately. She then places the zinc strip into the acid and bubbles form as the zinc looks like it disappears. The combined mass afterward is less than the original.
Chemistry
2 answers:
salantis [7]3 years ago
6 0

Answer:

Explanation:

When we react Hydrochlorid Acid with zinc we have the following reaction:

2HCl(aq) + Zn(s) --> ZnCl2(aq) + H2(g)

The hydrogen gas formed is lost to the environment, so we can affirme that in the start we have the mass for all the H, Cl and Zn atoms in the solution, but after the reaction occurs, we have only the mass for the Cl and Zn atoms.

That's why the mass is less than the original.

The law that the student was told is only applied to closed environments.

Eva8 [605]3 years ago
4 0
I think the combined mass was less afterward than the original mass due to escape of hydrogen gas in the atmosphere. According to the law of conservation of mass, mass is conserved and does not change in a chemical reaction which occurs in a closed system. However in an open system the mass may not be conserved and may change due to release of gases to the atmosphere. Like in this case, hydrogen gas produced in the reaction was released to the atmosphere thus reducing the final mass.
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Work the following question out on your own sheet of paper and submit a picture of your work:
valina [46]

Answer:

Heat  absorbed by water = 3985.26 j

Explanation:

Given data:

Mass of water = 75 g

Initial temperature = 20.0°C

Final temperature = 32.7°C

Specific heat of water  = 4.184 j/g.°C

Heat  absorbed by water = ?

Solution:

Specific heat capacity:

It is the amount of heat required to raise the temperature of one gram of substance by one degree.

Formula:

Q = m.c. ΔT

Q = amount of heat absorbed or released

m = mass of given substance

c = specific heat capacity of substance

ΔT = change in temperature

ΔT = 32.7°C - 20°C

ΔT = 12.7 °C

Q = 75 g ×4.184 j/g.°C ×12.7 °C

Q = 3985.26 j

7 0
3 years ago
What is the best name for this molecule? Explain your naming process.
iogann1982 [59]

Hi!


The best possible name for this molecule would be: 4 - ethyl - 1 - heptene or 4 - ethylhept - 1 - ene


We always name the molecule with respect to the longest chain (in a branched molecule), taking both atoms of carbon participating in the double bond into account too. In our case, this gives us a 7 Carbon chain - hept

ene - is the suffix that is indicative of the molecule being an alekene.

<em>So we know it is a branched heptene molecule</em>

We add the number where the double bond occurs either before ene, or before heptene as a rule.

<em>Note: We always start with the end of the chain from where the double bond is the closest, and number the carbons accordingly.</em>

The title and position of the branch always comes at the start. In our case the branch is a two carbon chain, and an alkane, so it would be an ethyl branch. This branch occurs at carbon number 4


Hence, the correct names would be:

<em>4 - ethyl - 1 - heptene</em> or <em>4 - ethylhept - 1 - ene</em>


Hope this helps!

7 0
3 years ago
Match each chemical reaction with the type of reaction that best describes it.
r-ruslan [8.4K]

2 Al + 6 HCl → 2 AlCl₃ + 3 H₂ (single displacement)

Ca + Br₂  → CaBr₂ (synthesis)

4 NH₃ + 5 O₂  → 4 NO + 6 H₂O (combustion)

2 NaCl → 2 Na + Cl₂ (decomposition)

FeS + 2 HCl → FeCl₂ + H₂S (double displacement)

single displacement - is a chemical reaction of the following type: A + BC → AC + B

double displacement - is a chemical reaction of the following type: AB + CD → AC + BD

synthesis - the chemical product is obtained by combining in a synthesis the constituent elements

combustion - usually a exothermic reaction of a particular compound with oxygen

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8 0
3 years ago
What is the mass in grams of ba(io3)2 can be dissolved in 500 ml of water at 25 degrees celcius?
lesya [120]

The mass of Ba(IO3)2 that can be dissolved in 500 ml of water at 25 degrees celcius is 2.82 g

<h3>What mass of Ba(IO3)2 can be dissolved in 500 ml of water at 25 degrees celcius?</h3>

The Ksp of Ba(IO3)2 = 1.57 × 10^-9

Molar mass of Ba(IO3)2 = 487 g/mol?

Dissociation of Ba(IO3)2 produces 3 moles of ions as follows:

Ba(IO_{3})_{2} \leftrightharpoons Ba^{2+} + 2\:IO_{3}^{-}

Ksp = [Ba^{2+}]*[IO_{3}^{-}]^{2}

[Ba(IO_{3})_{2}] =  \sqrt[3]{ksp} =\sqrt[3]{1.57 \times  {10}^{ - 9} } \\  [Ba(IO_{3})_{2}] = 1.16 \times  {10}^{-3} moldm^{-3}

moles of Ba(IO3)2 = 1.16 × 10^-3 × 0.5 = 0.58 × 10^-3 moles

mass of Ba(IO3)2 = 0.58 × 10^-3 moles × 487 = 2.82 g

Therefore, mass Ba(IO3)2 that can be dissolved in 500 ml of water at 25 degrees celcius is 2.82 g.

Learn more about mass and moles at: brainly.com/question/15374113

#SPJ12

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